Low profile audio speaker
A symmetrically loaded, shallow suspension speaker with stiff diaphragm having a minimum dimension that is greater than the diameter of the magnet that drives the diaphragm thus allowing the suspension of the diaphragm to extend nearly to the bottom of the speaker basket on the maximum inward excursion of the voice coil and diaphragm such that the suspension operational depth is not the limiting factor of the overall height of the speaker. The elements of the suspension system are designed to maximize the spacing between the inner and outer portions of the suspension, thus minimizing the possibility of wobble in the speaker. The speaker design maximizes air movement in a given mounting depth with a configuration that optimizes the operation of the moving parts that complements the fixed mechanical structural configuration of the non-moving parts in either an overhung or underhung configuration. The design also accommodates user replacement of the voice coil or cone.
This is a divisional of application of a application of the same title having Ser. No. 10/058,868 , filed Jan. 28, 2002, that issued as U.S. Pat. No. 6,675,931, on Jan. 13, 2004, which is a Continuation In Part application of application having Ser. No. 09/542,155, filed Apr. 4, 2000, that issued as U.S. Pat. No. 6,460,657, on Oct. 8, 2002, which is a Continuation In Part application of application Ser. No. 09/201,398, filed Nov. 30, 1998 that issued as U.S. Pat. No. 6,044,925, on Apr. 4, 2000.
BACKGROUND OF THE INVENTION1. Field of the Invention
This invention relates to loud speakers and in particular to the construction of low profile audio speakers.
2. Description of the Related Art
A goal of sound reproduction equipment is to provide a life-like sound quality to the listener. Lifelike sound quality is understood to be best achieved when a sound system including the speakers have a flat frequency response curve throughout the range of sound frequencies audible to the human ear, generally 20 to 20,000 Hz. A normal speaker cabinet has an electro magnetically driven speaker cone sealed to an opening in the wall of a sealed cabinet. This arrangement provides a drooping frequency response curve (e.g., 22 in the graph 20 of FIG. 1).
The graph 20 of
In an effort to offset the effects of a rigid sealed cabinet and avoid the spatial requirements necessary when attempting to create ports or tube ports with speakers low frequencies, passive radiators (generally configured like speakers, but without the electro mechanical driver) have been placed in a secondary opening of the walls of the speaker cavity to reduce the drop-off of the loudness at low frequencies. An example of the improvement in the frequency response when such a passive radiator is installed is shown as plot 24 in FIG. 1. An example of the improvement in the frequency response attributable to the installation of a prior art passive radiator can be understood by reviewing plot 26 in FIG. 2. Note that the drop in the frequency response curve at lower frequencies in plot 26 is very severe before the range of inaudible frequencies 28 is reached. In this configuration, AREA2, the area under the curve to the right of the peak above a minimum loudness level, is larger than AREA1which is the area under the curve to the left of the peak. This imbalance is indicative of the relative distortion that can be heard as the loudness of the passive radiator nosedives and falls below an audible loudness. The low frequency loudness and energy are not balanced with the high frequency loudness and energy. The area under the curves provide a measure of the imbalance.
Recent trends in the audio systems market have been leaning towards enhancing the bass or sub-woofer response of the audio reproduction systems, so that even if a sound is below the low limit of the range of audible sound, the sound level is high enough so that the listener, although he or she cannot “hear” the sound with ears, they can “feel” the sound as parts of their body are hit by the low frequency waves. At low frequencies, a limitation of passive radiators has been that the low frequencies require large displacements of the moveable radiator elements. Such large displacements can exceed the available range of motion of moveable radiator elements. For example. In
In the instance when a passive radiator constructed solely of a speaker cone is connected only as its peripheral rim to an annular support surface in the wall of a speaker, for example, as shown in the to Klasco U.S. Pat. No. 4,207,963, a larger range of travel is available to accommodate large movable element displacements experienced at high volume and low frequencies. However, the use of a surround around the perimeter of the top of the cone and the cone shape produces cone wobble which also distorts the sound. The object of the Klasco patent was to arrange active elements to reduce the wobble in the passive radiator.
In the instance where a lone speaker cone suspended in a cavity opening is used, the response of the passive radiator during low frequency cycles as the cone is forced outward and pulled inward can be non-linear as the flexible member (surround) holding the cone tends to have different non-linear force to displacement characteristics when being stretched outwardly as compared to when it is being stretched inwardly.
The limitations on travel as shown in the prior art described in
The spatial requirement of the prior art passive radiators is also a drawback. The prior art passive radiators are quite large and bulky and extend a large distance into any sealed cavity. This spatial requirement must be taken into account when designing features and companion speakers to fit into the sealed cavity.
Recently there has been an increasing demand for loudspeakers for use in a very compact/shallow space. This demand was born by consumer appetite for louder sound grew couple with the desire for less obtrusive speakers. Recently, home audio consumers have begun a major shift from larger, conventional loudspeakers housed in cabinets that stand alone in the room—to smaller piston speakers that mount within the wall of a house. The available depth in in-wall locations is dictated by the use of 2×4 studs during construction thus creating a space that is less than 4″ deep.
This need for shallow, low profile speakers are not limited to meeting the home audio demand. Such low profile speakers also have application in cars, boats, airplanes and other locations that will benefit from the depth reduction without taxing the sound pressure level. In cars for example, the available mounting depth behind the door panel is much less than the minimum height of conventional speakers. In order to use conventional speakers in such locations, it is nearly always necessary to use a raised grill cover over the speaker since it necessary to have a portion of the speaker heigh extend above the surface of the door panel into the passenger compartment.
For the most part, subwoofer construction has followed conventional technology the use of an oscillating diaphragm that responds to a varying magnetic field developed by an applied audio signal. That varying magnetic field causes the diaphragm to be attracted and repelled to and from the intermediate position where the diaphragm rests when no audio signal is applied to the speaker. For the most part, current speaker technology uses a loudspeaker made of a rigid diaphragm, or “cone”, suspended within a speaker frame, or “basket” around the outer edge with a flexible membrane, or “surround”. This membrane allows the cone to move inward and outward when driven by a varying magnetic field resulting from the application of an audio, or “music”, signal applied to the speaker.
Over the years speakers have been designed with a convention structure—a cone connected to the outer part to a speaker frame, or basket, through a flexible membrane (surround). To develop a back-pressure wave and to control axial movement of the cone, designer installed a secondary part called a “spider” that also connects the inner part of the cone to the speaker frame. Almost all spider materials used are made of cloth that has been treated and pressed in a heated die to form the shape of the spider that was sought. Conventional speakers require a huge mounting depth that render them useless in shallow spaces where consumers now wish to place speakers. For example, a conventional 10″ diameter speaker, with an excursion of +/−1″ requires a mounting depth of at least 7″. Moreover 12″ diameter conventional speakers requires a mounting depth of at least 7″ to 8″. Hence conventional speakers clearly will not fit in shallow spaces, such as walls where the mounting depth is limited to about 3.5″, or less, unless a smaller diameter conventional speaker is used. Thus, consumer demand has created a need that conventional speakers can not meet and still provide the performance desired by the consumer. Therefore there is a need to develop loudspeakers that have a large piston area with a minimum mounting depth. Low profile speakers designed using the present invention meet that need.
SUMMARY OF THE INVENTIONAn embodiment according to the invention overcomes the drawbacks of the prior art by providing a generally linear response by configuring two speaker surrounds opposite one another so that any non-linearities in the spring constant between an outward displacement versus an inward displacement are generally cancelled and a pseudo linear spring constant is developed throughout the central range of travel of the passive radiator moveable elements.
In an embodiment according to the invention an inner surround encircles and has an inner edge fixed to the perimeter of an inner center member which is generally a flat disk and may be a flat disk diaphragm. The arch of the surround between the inner edge and the perimeter edge of the inner surround extends in a first direction. An outer surround encircling and having an inner edge fixed to the perimeter of an outer center member is configured so that its arch extends in a second direction which is opposite the first direction. A connection member or mass is fixed to and between the inner center members and the outer center member causes the two to move together and in parallel. The connection member may be a specially sized mass to tune the passive radiator for resonance at a particular frequency.
Variations of embodiments according to the invention include using a ratio of the size of the inner center member to the outer center member or outer center member to the inner center member of between 0.8 and 1, the calculation of the ratio will be such that the rat o will always be 1 or less. Another embodiment provides the inner central member and outer central member to be connected and integral as one piece with an annular spring (elastic) member between the central integral inner and outer member core and the surrounding speaker frame opening. A cut out section of the wall of the speaker cabinet, for example can form the central diaphragm core, and the application of an elastic flowable substance that can be formed in place to form an elastic bond between the core and the surrounding support frame (usually a hole in the speaker cabinet) by using a formable elastic substance that can be formed into a desired shape in flowable gel or liquid type state. Where the flowable substance sets up to have acceptable elastic qualities such as might be found when using a spider or surround of the current design in that location.
A further aspect of the invention involves structures and methods which enhance embodiments according to the invention by eliminating high pressure air between surround rolls during long strokes of the passive element by providing an air vent system. This system prevents creation of a high-pressure secondary air cabinet that slows the response.
A still further aspect of the invention relates to the utilization of multiply configured concentric surrounds in a long stroke passive speaker configuration to provide a high quality sound without noticeable group delay while still providing high SPL (sound pressure levels). A progressive roll passive system utilizes progressively smaller surround roll diameters to achieve high sound pressure levels with minimal distortion with a short overall height.
Another aspect of the present invention builds on the invention embodiments discussed above to provide a symmetrically loaded, shallow suspension speaker. In the speaker embodiments of the present invention, the symmetrically loaded, shallow suspension supports a substantially stiff diaphragm that functions similarly to the “cone” of the prior art. In the present invention the diaphragm, or cone, is made of a material such as honeycomb, thin aluminum, and other composite and non-composite light-weight materials; conventional cone materials will not work in this application since the diaphragm is substantially flat and light-weight. This flat diaphragm is suspended by the outermost edge with a suspension system that is entirely outside the diameter of the magnet, thus allowing the suspension to extend to nearly the bottom of the speaker basket on the maximum inward excursion of the voice coil and diaphragm. Thus, the suspension operational depth is not the limiting factor of the speaker basket design and the actual mounting depth of the speaker. Note that mounting depth and cone wobble control are interrelated in the speakers of the present invention; the closer the outer portion of the suspension is to an inner one, the chance of wobble increases as the the mounting depth of the speaker becomes shallower. As will be seen below in the detailed description of the various embodiments of the present invention, the elements of the suspension system of the present invention have been designed maximize the spacing between the inner and outer portions of the suspension system, thus minimizing the possibility of wobble in the low profile speakers of the present invention.
The various embodiments of the present invention permit the designer to maximize air movement in a given mounting depth with a configuration that optimizes the operation of the moving parts (i.e., diaphragm, suspension and voice coil) in the electromagnetic environment that complements the fixed mechanical structural configuration of the non-moving parts. In one embodiment, this invention allows the designer to have an over excursion (outward/inward limiter) that is optimized with the available mounting depth. For example, the present invention allows the designer to have a 15″ diameter speaker that fits in a mounting depth of as little as 3.5″ with a diaphragm excursion of approximately ±1″, while a conventional speaker with the same size working piston requires a mounting depth of 6″ to 7″.
The present invention also includes several embodiments that allow the user of the speaker to replace the voice coil, or the voice coil and the cone or diaphragm, should they becomes damaged. This would be an attractive option for performers that have a speaker fail during a performance when a speaker is over-driven or dropped.
An embodiment according to the invention is shown is
In a normal speaker configuration where only one surround is used. e.g., at the perimeter of a speaker cone, there is a non-linear characteristic in the restoring force relative to displacement for a normal half circle type surround. The restoring force is the force that restores the speaker assembly to its neutral position for example during transportation and/or when the speaker is not in use. The non-linearity of the stressing of the inside surface of the arch versus the outside surface of the arch as the surround is stretch by the displacement of a center disk or speaker cone creates a small but detectable distortion. In such arrangements increased air pressure due to the sound waves does not move the diaphragm at the same rate when subject to similar pressure gradients, but rather the air starts to become compressed and generate reflected pulses as a result of the non-movement or slower movement of the diaphragm due to the different displacement rates. As the diaphragm in the passive radiator is exposed to air pressure due to sound volume, the use of two oppositely facing surrounds provide an effective compromise and an improvement over the use of the single surround by providing an approximately linear pressure to displacement relationship irrespective of whether a sound wave is positive (for example, causing the diaphragm to move out) or negative (for example, causing the diaphragm to move inward).
The use of two oppositely facing surrounds which are fixed to each other and with virtually no separation, for example, as shown in
A configuration according to the present invention has the additional advantage of eliminating the wobble problem by the use of a parallelogram-type parallel link arrangement where the two diaphragms 106, 110 each have their perimeters act as two ends of a fixed link of a parallelogram type linkage. A second set of fixed links are the corresponding inner and outer walls to which the outside perimeter of the surrounds 114, 118 are fixed. The moveable links connecting the two fixed links are the surrounds which extend between the perimeter of the central diaphragm 106, 110 and the inner perimeter of the outer ring for example, 134 in FIG. 9. Using this configuration will reduce any wobble by creating additional resistance to a wobbling effect due to the two surrounds being mounted in parallel at the end of what effectively amounts to an elastically extendible pivoting lever arm. Thus any configuration according to the invention for example as shown in
The construction of the passive radiator is quite simple as shown in
An alternative configuration using a series of surrounds 142, 144 provides that the arches of 146, 148 such surround must extend in a single direction. This configuration while not optimum does provide the advantage over the prior art of eliminating or substantially eliminating the wobble problem referred to earlier. In a configuration as shown, the spring constants will be unequal and the non-linearity of the spring constant plot will be attenuated by the use of two surrounds whose spring constants add to exacerbate their distortion from linear.
A review of the plot as shown in
An aspect of the present invention further enhances the sound performance. The closure of spaces between opposing surround rolls can cause a high pressure secondary cabinet that slows down the response. A pressure relief system is provided to allow the air trapped between two diaphragms to have the same pressure as that in the speaker box (or alternately outside the speaker box) via port holes that are large enough to keep the air speed through these holes under 1% of the speed of sound with a value of about 12 ft/second. Since these numbers are worse at the passive resonance frequency, this calculation can be optimized for the maximum excursion calculation. The pressure relief port can be implemented best through holes in the inner surround that leak air directly into the speaker box.
Progressive Surround Roll Radiator Construction
An aspect of the present invention that utilizes low profile large stroke passive radiators includes the use of a progressive roll system that further enhances the performance of passive radiator design.
Low frequency instruments emanate sound waves via vibration of diaphragms. These diaphragms oscillate at a low frequency. The oscillations have maximum amplitude in the center of the diaphragm with a proportionally reduced oscillation across the diaphragm with no oscillatory motion at the diaphragm frame. The dynamic oscillatory activity associated with a bass drum is useful in illustrating the dynamic relationship between the oscillating diaphragm and the emanating sound wave.
When a drummer strikes the center of the bass drum, the striking force bends the diaphragm inward such that the diaphragm shape is no longer flat, but is deformed in an approximation of a cone or sphere. The pressure inside the drum increases and is transferred to the other side of the drum, and results in an outward movement of the diaphragm. The tension and the phase angle of the sound wave as they bounce back and forth allow the signal to decay in a harmonic fashion. The decay time is directly related to the diaphragm diameter, tension and the distance between the two diaphragms at any fixed frequency. Utilizing the apparatus and methods according the invention provides that opportunity to approach a bass drum sound when using relatively smaller 12″ and 15″ speakers. To approach the desired condition the passive radiator is matched with the speaker has to be tuned low enough and has to move out axially to produce the same air movement, i.e., SPL at any given frequency is strictly related to the quantity of air moved at that frequency. The quality of sound must also be maintained. The quality of sound is measured by the group delay. A group delay is the time versus frequency curve that describe the response time delay at any given frequency. A 20 ms delay at 20 Hz is said to be audible distortion. Group delay is directly proportional to the diaphragm excursion. A long excursion creates long group delays.
One example of a surround structure used in a speaker is to used a single large, surround, a cross section of which is pictured in FIG. 25A. The single surround provides a large axial stroke and an even larger stroke if a an elliptical cross section (as shown by the solid line) as opposed to the circular cross section (as shown by the dashed line) is used. While this configuration has a good potential for large axial movements, the large roll diameter allows side to side instability at even small increments of axial excursion. A plot of relative excursion versus relative force for an approximation of an elliptical surround configuration is shown as curve 212 as pictured in FIG. 25. The restoring force is relatively small at small axial displacements (extensions) and rises rapidly as the extension increases.
A second example of a surround structure is the use of what are known as an “m” surround (two or more side by side surrounds).
A set of cross sectional views of a passive speaker arrangement using the single large surround and the three small surrounds (of
To optimize an apparatus according to the present invention large qualities of air must be moved, but using the shortest most even diaphragm possible, like a bass drum. The diaphragm movement must decay uniformly at the side, i.e., as the diaphragm approaches the stationary frame. The movements must be axial and not side to side as such movements will cause a wobble that produces audible distortion.
An embodiment according to the invention which overcomes the drawbacks of the previously discussed arrangements, is to use a progressive roll diameter configuration, for example a cross section of which is shown in FIG. 25C. In this arrangement a set of three surrounds are provided, the outer surround being the largest, with surrounds internal to the outer one being progressively smaller. This arrangement provides a non uniform position specific extension characteristic, an approximation of which is shown by the curve 216 in FIG. 25. An understanding of the localized position based extension of the progressive surround arrangement can be understood by correlating the plot of the curve 216 in
In
As shown in the
The sizing of the surrounds closest to the perimeter compared with the surrounds positioned closer to the center of the vibrating element depends on two important considerations:
-
- 1. Linear stiffness where by the closest to the perimeter (next to the frame) surround will approach maximum excursion just as the range of excursion for the next adjacent surround begins a larger relative motion. This is necessary to produce a distortion free response. If this is not respected a harmonic distortion will overwhelm the fundamental signal and will create a complex signal out of a single tone.
- 2. The outer roll diameter, whereby the piston diameters relates to the amount of movement for a particular piston and roll diameter. Also the second (inside the outer) roll diameter and the second piston diameter are related in a similar way. Furthermore the outer roll diameter and the inner roll diameter are related to each other in a proportional way such that the outer roll is larger than the inner one following the arc of sphere or a cone (e .g., the inner is no greater than 80% of the diameter of the immediately adjacent outer roll diameter). Once the outer diaphragm diameter (Do—diameter outer) is selected (see
FIG. 25C ) and a maximum excursion distance associated with the outer piston (the diameter to the outside of the selected surround) is selected and the configuration of the progressive roil arrangement is set. Since the maximum axis travel equates to approximately 70% of the corresponding roll diameter (dro—diameter roll outer) a ratio of (Do/dro) the roll diameter is set and the distance to the next diaphragm inside the outer one is set, approximately correlating to Do minus dro. Using the three surround example, the middle surround has a piston diameter (Dm—diameter middle) and a corresponding roll diameter (drm diameter roll middle) such that the ratio (Do/dm)=(Dm/drm) holds true as surrounds progressively get smaller toward the center. These ratios of geometric quantities in practice are dependent on material properties and transitional variations and thus are approximately equal rather than being exactly so. There will be an optimum value for the next roll diameter based on the air quantity moved and speed (i.e., surround stiffness).
During long strokes, the air trapped between the diaphragms can have a high pressure secondary cabinet that slows down the response. To eliminate this problem, air ventilation holes are made in the inside diaphragm (similar to that described above). The ventilation holes must have enough window area to allow air to pass at a speed of no more than 12 ft/sec (approximately 1% of the speed of sound). These holes must be symmetrical so that they do not pose a bias to the surrounds.
Tube Arrangement
Another configuration according to the invention, showing a speaker and a passive radiator in an enclosure is shown in
Low Profile, Shallow Speaker Embodiments
The various embodiments of the present invention permit the designer to maximize air movement in a given mounting depth with a configuration that optimizes the operation of the moving parts (i.e., diaphragm, suspension and voice coil) in the electromagnetic environment that complements the fixed mechanical structural configuration of the non-moving parts. In one embodiment, this invention allows the designer to have an over excursion (outward/inward limiter) that is optimized with the available mounting depth. For example, the present invention allows the designer to have a 15″ diameter speaker that fits in a mounting depth of as little as 3.5″ with a diaphragm excursion of approximately ±1″, while a conventional speaker with the same size working piston requires a mounting depth of 6″ to 7″.
Additionally, there is a stiff, substantially flat diaphragm 404 with the diameter of the flat area being larger than the outer diameter of magnet 406. The outer most edge of diaphragm 404 is shown having a “V” shaped outer edge that extends downward and away at approximately 60°, however that specific angle is not critical to the design. Diaphragm 404 is ideally made of a material such as honeycomb, thin aluminum, or other composite and non-composite light-weight materials; conventional cone materials will not work in this application since the diaphragm is substantially flat and light-weight. Diaphragm 404 is suspended with two matched surrounds: an upwardly extending flexible surround 418 having an inner edge attached to the top of the outwardly extending leg of the “V” shaped edge of the diaphragm and an outer edge attached to the top, outer most flange of basket 402; and a downwardly extending flexible surround 420 having an inner edge attached to the bottom of the inner leg of the “V” shaped edge of the diaphragm and an outer edge attached to a point within basket 402 below the top, outer most flange. With surrounds 418 and 420 mounted in this way, maximum linearity of the inward/outward strokes of the speaker is achieved. Between the attachment points of surrounds 418 and 420, ventilation holes 426 have been formed around the circumference of basket 420. Attached to the lower center of diaphragm 404 is voice coil 412 that fits loosely around the upwardly extending portion of steel doughnut 410 with the upper most turn of the coil of voice coil 412 being spaced 0.5α below the inner surface of the diaphragm and the coil winding having a height of 2α in this overhung configuration. By making the height of the coil winding the same as the thickness of the magnet makes it possible to minimize the overall height of the speaker in every excited and unexcited positions of the diaphragm. With respect to each of the views of
In
In
Note that the outermost edge of suspension system 418, 420 and diaphragm 404 is entirely outside the outer diameter of magnet 406, thus allowing the suspension to extend below the top surface of ring 408 with surround 420 nearly extending to the bottom of the basket on the maximum inward excursion of the voice coil and diaphragm as shown in FIG. 36C. Thus, the suspension operational depth is not a limiting factor of the speaker basket design and the actual mounting depth of the speaker. As noted above the mounting depth and cone wobble control are interrelated in the speakers of the present invention; the closer the outer portion of the suspension is to an inner one, the chance of wobble increases as the mounting depth of the speaker becomes shallower. As can be seen in
By connecting the outer most side of bladder 422 to a lower point within basket 402 that is approximately horizontally even with the underside of the outer most leg of the “V” shaped edge of the diaphragm rocking of the diaphragm during speaker operation is minimized. Bladder 422 could be manufactured by injection molding and the wall thickness could be increased as necessary to achieve the desired performance. Additionally, to reduce internal pressure that develops during extreme in/out strokes, bladder 422 can have ventilation holes around the circumference to reduce internal pressure to allow air trapped within to leak into the space in which the speaker is mounted through ventilation holes 426. The overall height calculations for this embodiment are the same as for the first embodiment of FIG. 36A.
The third overhung, low profile speaker embodiment of
In this embodiment, diaphragm 404′ consists of to two elements—a flat ridged top disk 413 and a circular enclosure 409 to the top of which top disk 413 is coupled. Circular enclosure 409 has cylindrical open interior with an inner diameter that is greater than the diameter of assembly 410, 406, 408′ that opens to the opening in the basket. Through the center of bottom portion 411 of enclosure 409 is a circular hole that has a diameter substantially equal to that of voice coil 412 with the lower end thereof coupled within the bottom hole of enclosure 409. Voice coil 412 extends upward and fits loosely around the downwardly extending portion of steel doughnut 410′ with the lower most turn of the coil of voice coil 412 being spaced 0.5α′ above the inner surface of bottom portion 411 and the coil winding has a height of 2α′ In this overhung configuration. Additionally, the inner depth of enclosure 409 is 2α′. Extending radially outward from enclosure 409 is a ring with the outer edge undercut inward shown here at approximately 45°, however the undercut angle is not critical to the operation of the speaker. The outwardly extending ring of the enclosure is coupled to the mouth of the basket by surrounds 418, 420 similar to that shown in FIG. 36A.
In
In
Thus the unexcited height of the speaker in
The maximum outward excited height of the speaker in
Similarly, the maximum inwardly excited height of the speaker in
Diaphragm 404″″ of this embodiment has an outer edge that is a two tine, horizontally extending fork with the upper surface of diaphragm 404″″ forming a first tine 426 of the fork with the second tine 428 spaced apart from and below the first tine. In place of surrounds 418 and 420, the present embodiment utilizes a single support bladder 424 with a first mounting tab 430 extending outward for attachment to the outwardly extending flange of basket 402, and a second mounting tab 432 extending outward on the opposite side of the bladder from tab 430. Tab 432 is sized to fit between, and be captured within, the space between tines 426 and 428 on the outer edge of diaphragm 404″″. In the unexcited state of the speaker shown in
Namely, in
In
In
A second embodiment of an underhung, low profile speaker of the present invention is illustrated in FIG. 43. This embodiment is also similar to the first overhung embodiment of
The voice coil assembly in the upper portion of
The details of rings 444 and 446 are shown in
Also included is a cone 526 with surround 528 bonded to the outer edge of the cone. Beneath the center of cone 526 is a voice coil 520 on a bobbin with one lead 522 from the coil extending up the left side of the bobbin to the underside of the cone, and on the right side of the bobbin the other lead 524 of the coil also extends upward to the under side of the cone. The bobbin can either be permanently fixed to the under side of the cone, or it can with ring 444 (
Also connected to the underside of the cone, outside of, and spaced apart from, of the bobbin, is a downwardly extending cylinder that is approximately one third the length of the bobbin with an Internal thread at the lower end thereof. That cylinder includes a left conductive portion 516 and a right conductive portion 518 that are connected at their cone end to lead wires 522 and 524, respectively. Conductive portions 516 and 518 could be left and right sides of a ring such as ring 446, or lead wires 522 and 524 could be extended from the cone down into the Internal threads of 516 and 518.
The final step of assembly of such a speaker is the lowering of the cone/voice coil assembly to the mouth of basket 502 with the winding of the voice coil passing through the central cylinder supported by the spider with the windings of the coil extending to the magnet assembly. The cone/voice coil assembly is attached to the cylinder/spider assembly by mating the internal threads of the cylinder attached to the cone with the outer threads of the cylinder taking care to position the cone/voice coil assembly such that lead wires 522 and 524 are coupled to external connectors 510 and 508, respectively. Once the voice coil is positioned as such, the final step of assembly is the placement of the outer edge of surround 528 to the outside of the rim on the basket flange opposite the concave half circle groove 532. Then elastic ring 530 is placed around the so located outer edge of the surround to seat the edge of the surround in groove 532 and retained in that position by elastic ring.
With a speaker of this design, a user of such a speaker will be able to replace either the voice coil of the cone should they, or the surround be however damaged. Also the user will be able to interchange the cone and/or voice coil with those of a different design or configuration to produce a different audio response and sound from the speaker.
While the invention has been described with regard to several specific embodiments. Those skilled in the art will recognize that changes can be made in form and detail without departing from the spirit and scope of the invention. One skilled in the art will also find it obvious to extend the techniques discussed with respect to a passive radiator to and active speaker, and to also extend the techniques discussed relative to an active speaker to a passive radiator. This is true since a passive radiator is basically the same as a speaker without the electromagnetic engine for moving the diaphragm of the passive radiator. Thus, the protection afforded hereby is as stated in the accompanying claims and equivalents thereof.
Claims
1. A loudspeaker with removable/replaceable cone and voice coil comprising:
- a frame having a bottom surface with a side portion extending upward from, and surrounding, said bottom surface, said side portion terminating in an exterior edge of a uniform height above said bottom surface and said exterior edge defining an opening having a first predetermined size and shape;
- a stiff diaphragm having an outer edge, a top surface and a bottom surface; said stiff diaphragm has a second size that is smaller than said first size and is substantially the same shape as said opening defined by the exterior edge of the frame;
- a first flexible suspension surrounding the outer edge of the diaphragm having an inner edge attached to the outer edge of the diaphragm and an outer edge attached to the exterior edge of the frame, with the combination of said diaphragm and first suspension having a size and shape that is substantially the same as the first size and shape;
- an audio motor including: a magnet mounted centrally to the bottom surface of the frame; a thin walled bobbin having a first length, a first diameter, and first and second ends; and a voice coil wound closest to the first end of the bobbin; wherein the second end of the bobbin is attached centrally to the bottom surface of the diaphragm to move the stiff diaphragm, when the first suspension is coupled to the frame, inward and outward relative to the bottom surface of the frame in response to an electrical signal applied to the voice coil that interacts with the magnet to move the bobbin;
- a first cylinder having a second length that is shorter than the first length, and an inner diameter that is larger than the combined first diameter of the bobbin and a thickness of the voice coil wound thereon; and
- a second flexible suspension attached to, and surrounding, an outer surface of said first cylinder, and extending and attached to a point on an interior surface of the side portion of the frame between the exterior edge and the bottom surface of the frame;
- wherein when the loudspeaker is assembled the end of the bobbin with the voice coil thereon extends through the first cylinder and interacts with the magnet.
2. A loudspeaker as in claim 1 wherein the combination of said diaphragm and first flexible suspension is removably attached to the exterior edge of the frame.
3. A loudspeaker as in claim 2 further includes an elastic ring located around the exterior edge of the frame with the outer edge of the first flexible suspension between the elastic ring and the exterior edge of the frame.
4. A loudspeaker as in claim 1 wherein said bobbin is removably attached to said diaphragm.
5. A loudspeaker as in claim 1 wherein:
- said loudspeaker further includes a second cylinder having first and second ends, a third length that is shorter than said first length and a second diameter that is greater than said first diameter, with said first end connected to the bottom surface of the diaphragm concentrically with, and encircling said first end of, the bobbin, wherein an inner surface of the second end of the first cylinder is threaded; and
- an end of said first cylinder is externally threaded to mate with the threaded portion of said second cylinder closest to said exterior edge of the frame when the loudspeaker is assembled.
6. A loudspeaker as in claim 5 wherein the combination of said diaphragm and first flexible suspension is removably attached to the exterior edge of the frame.
7. A loudspeaker as in claim 6 further includes an elastic ring located around the exterior edge of the frame with the outer edge of the first flexible suspension between the elastic ring and the exterior edge of the frame.
8. A loudspeaker as in claim 5 wherein said bobbin is removably attached to said diaphragm.
9. A loudspeaker as in claim 5 wherein:
- the threaded end of said first cylinder includes a first bifurcated, externally threaded ring affixed to the first cylinder, the first bifurcated ring includes two electrically conductive portions and two non-conductive portions alternately around the edge of the first cylinder;
- the second end of said second cylinder includes a second bifurcated, internally threaded ring affixed to the second cylinder, the second bifurcated ring includes two electrically conductive portions and two non-conductive portions alternately around the edge of the second cylinder;
- said voice coil being an electrically conductive wire coil with the coil having two free ends, said two free ends of wire dressed to the second end of the bobbin, then to the first end of the second cylinder and then to the second end of the second cylinder with each of the wire free ends in electrical contact with a different one of two electrically conductive portions of the second ring;
- said loudspeaker further including: a pair of electrically conductive wires dressed across said second suspension toward the frame; and a pair of terminals mounted on the frame each connected to a different one of the wires dressed across said second suspension toward the frame with said terminals disposed to be connected to an amplifier to receive electrical signals to drive said voice coil; and
- when said loudspeaker is assembled first and second cylinders are aligned one with the other with the first and second conductive portions of the first ring being in contact with a different one of the first and second conductive portions of the second ring.
10. A loudspeaker as in claim 5 wherein:
- said first cylinder includes two electrically conductive cylinder portions and two non-conductive cylinder portions alternately therearound forming the first cylinder;
- said second cylinder includes two electrically conductive cylinder portions and two non-conductive cylinder portions alternately therearound forming the second cylinder;
- said voice coil being an electrically conductive wire coil with the coil having two free ends, said two free ends of wire dressed to the second end of the bobbin and then to the first end of the second cylinder with each of the wire free ends in electrical contact with a different one of two electrically conductive cylinder portions of the second cylinder;
- said loudspeaker further including: a pair of electrically conductive wires dressed across said second suspension toward the frame; and a pair of terminals mounted on the frame each connected to a different one of the wires dressed across said second suspension toward the frame with said terminals disposed to be connected to an amplifier to receive electrical signals to drive said voice coil; and
- when said loudspeaker is assembled first and second cylinders are aligned one with the other with the first and second conductive cylinder portions of the first cylinder being in contact with a different one of the first and second conductive cylinder portions of the second cylinder.
Type: Grant
Filed: Sep 30, 2003
Date of Patent: Mar 8, 2005
Inventor: Joseph Yaacoub Sahyoun (Redwood City, CA)
Primary Examiner: Shih-Yung Hsieh
Assistant Examiner: Edgardo San Martin
Attorney: Allston L. Jones
Application Number: 10/675,853